Consumer unit replacement in Epping Forest and West Essex

What does a consumer unit actually do?

It is the point where the electricity entering your home is split into circuits, and where each circuit gets a device to cut the power if something goes wrong. A main switch isolates the whole house. Behind it sit the circuit breakers or fuses for the lights, the sockets, the cooker, the shower and so on, and on newer boards the residual current devices that cut off a circuit the moment current leaks to earth. People still call it the fuse box or the fuse board, and all three names mean the same thing.

How do I know mine is due for replacement?

Age alone does not condemn a board, but several things suggest it is time:

• rewirable fuses, where fuse wire is wound between two screws in a ceramic or plastic carrier
• no residual current devices at all, or a single one covering the whole house
• a wooden backboard, a cracked or loose cover, or scorch marks around a fuse
• so few spare ways that a previous electrician has doubled circuits up on one breaker
• a plastic enclosure fitted before the current rules on containing fire, which an inspection usually records as an improvement rather than a danger, which an inspection usually records as an improvement rather than a danger
• a planned extension, loft conversion, electric shower or car charger that the old board cannot take

An electrician will also want to replace a board that an inspection has given a code needing attention.

What is different about a modern board?

Boards fitted in homes today have a metal case, because the Wiring Regulations, BS 7671, require consumer units in domestic premises to be in a non-combustible enclosure so that a fault inside cannot start a fire outside the box. Many new boards use an RCBO on each circuit, which combines overload and earth-leakage protection, so a fault in the garden no longer plunges the kitchen into darkness as well. Many also carry a surge protection device to shield electronics from spikes on the supply, and a proper schedule of labels. Ask what the electrician proposes and why, since the layout of the board should suit how your home uses power.

Will the old wiring need looking at first?

Yes, and this is the part that surprises people. A new board is only as good as the circuits connected to it, and old fuses may have been tolerating faults that modern protection will not. Before connecting anything, the electrician tests each circuit: insulation resistance, earth continuity, polarity and the earth fault loop. They will also check that the main earth and the bonding to the gas and water pipes are present and the right size, because a board change is the point at which those must be brought up to standard. Faults found at this stage need putting right before the circuit can go onto the new board, and the electrician should tell you about each one, and what it will cost, before doing it.

Is replacing a consumer unit notifiable work?

It is. In England, replacing a consumer unit is notifiable under Part P of the Building Regulations. Either the electrician is registered with a government-authorised competent person scheme and notifies the work on your behalf, or the council's building control must be told before the work starts and will charge to inspect it. On completion you should receive an Electrical Installation Certificate with the schedule of test results, and in due course a certificate confirming that the work complies with the Building Regulations. Keep both with the house papers, because a buyer's solicitor will ask for them when you sell. You can look up an electrician on the public register of their scheme before the work starts.

What happens on the day?

The power to the whole house is off for most of the job, so plan around the fridge, the freezer and anyone working from home. The electrician needs clear access to the board and to the meter, and the main fuse will need to be pulled or an isolator switch used so that the board can be disconnected safely. If there is no isolator between the meter and the board, your supplier or the network operator may need to fit one, which can affect timing, so mention it when you enquire. Once the new board is in, every circuit is tested again and the results are recorded on the certificate.

Can the board be moved at the same time?

Often, and a board change is the natural moment to do it. A board in a cupboard full of coats, high on a kitchen wall or in a damp porch can be relocated nearby if the incoming cables allow. Moving it far means extending the tails from the meter, which may involve the supplier, so say where you would like it and the electrician can tell you whether that is realistic.

What should the enquiry include?

• a photo of the existing board with the cover closed, and one of the meter
• the type of home and roughly when it was built
• anything planned that will add load, such as an electric shower, a hot tub or a heat pump
• whether you have a recent inspection report and the codes it recorded
• whether you own the home or rent it
• your postcode

If a local electrician covers your postcode and you agree, that single electrician is sent your enquiry. If nobody does, we say so and nobody sees your details.